Administration and Maintenance

Understanding build parameters

Please refer to Build Parameters for information on how options are configured within OSBS builds.

Configuring osbs-client

When submitting a new build request to OSBS as a user, this request is for an orchestrator build. When the orchestrator build wants to create worker builds it also does this through osbs-client.

As a result there are two osbs.conf files to consider:

  • the one external to OSBS, for creating orchestrator builds, and
  • the one internal to OSBS, stored in a Kubernetes secret (named by client_config_secret) in the orchestrator cluster

These can have the same content. The important features are discussed below.


The parameter can_orchestrate defaults to false. The API method create_orchestrator_build will fail unless can_orchestrate is true for the chosen instance section.


reactor_config_map specifies the name of a Kubernetes configmap holding Server-side Configuration for atomic-reactor. A pre-build plugin will read its value from REACTOR_CONFIG environment variable.


When client_config_secret is specified this is the name of a Kubernetes secret (holding a key osbs.conf) for use by atomic-reactor when it creates worker builds. The orchestrate_build plugin is told the path to this.


When token_secrets is specified the specified secrets (space separated) will be mounted in the OpenShift build. When “:” is used, the secret will be mounted at the specified path, i.e. the format is:

token_secrets = secret:path secret:path ...

This allows an osbs.conf file (from client_config_secret) to be constructed with a known value to use for token_file.

Node selector

When an entry with the pattern node_selector.platform (for some platform) is specified, builds for this platform submitted to this cluster must include the given node selector, so as to run on a node of the correct architecture. This allows for installations that have mixed-architecture clusters and where node labels differentiate architecture.

If the value is none, this platform is the only one available and no node selector is required.

Platform description

When a section name begins with “platform:” it is interpreted not as an OSBS instance but as a platform description. The remainder of the section name is the platform name being described. The section has the following keys:

architecture (optional)
the GOARCH for the platform – the platform name is assumed to be the same as the GOARCH if this is not specified


Specifies the build image (AKA “buildroot”) to be used for building container images, to be set in the Build/BuildConfig OpenShift objects under the .spec.strategy.customStrategy.from object. This can be a full reference to a specific container image in a container registry; or it can reference an ImageStreamTag object.

Updating this globally effectively deploys a different version of OSBS.

It takes one of the following forms:

use the image from the specified OpenShift ImageStreamTag
pull the image from the specified pullspec (including registry, repository, and either tag or digest)

Deploy OSBS on OpenShift


The orchestrator cluster will have a service account (with edit role) created for use by Koji builders. Those Koji builders will use the service account’s persistent token to authenticate to the orchestrator cluster and submit builds to it.

Since the orchestrator build initiates worker builds on the worker cluster, it must have permission to do so. A service account should be created on each worker cluster in order to generate a persistent token. This service account should have edit role. On the orchestrator cluster, a secret for each worker cluster should be created to store the corresponding service account tokens. When osbs-client creates the orchestrator build it must specify the names of the secret files to be mounted in the BuildConfig. The orchestrator build will extract the token from the mounted secret file.

Server-side Configuration for atomic-reactor

This will list the maximum number of jobs that should be active at any given time for each cluster. It will also list worker clusters in order of preference. It may also contain additional environment configuration such as ODCS integration.

The runtime configuration will take the form of a Kubernetes secret with content as in the example below:

  - name: prod-x86_64-osd
    max_concurrent_builds: 16
  - name: prod-x86_64
    max_concurrent_builds: 6
    enabled: true
  - name: prod-other
    max_concurrent_builds: 2
    enabled: false

  - name: prod-ppc64le
    max_concurrent_builds: 6

  - name: release
    keys: [AB123]
  - name: beta
    keys: [BT456, AB123]
  - name: unsigned
    keys: []
  # Value must match one of the names above.
  default_signing_intent: release


This maps each platform to a list of clusters and their concurrent build limits. For each platform to build for, a worker cluster is chosen as follows:

  • clusters with the enabled key set to false are discarded
  • each remaining cluster in turn will be queried to discover all currently active worker builds (not failed, complete, in error, or cancelled)
  • the cluster load is computed by dividing the number of active worker builds by the specified maximum number of concurrent builds allowed on the cluster
  • the worker build is submitted to whichever cluster has the lowest load; in this way, an even load distribution across all clusters is enforced

There are several throttles preventing too many worker builds being submitted. Each worker cluster can be configured to only schedule a certain number of worker builds at a time by setting a default resource request. The orchestrator cluster will similarly only run a certain number of orchestrator builds at a time based on the resource request in the orchestrator build JSON template. A Koji builder will only run a certain number of containerbuild tasks based on its configured capacity.

This mechanism can also be used to temporarily disable a worker cluster by removing it from the list or adding enabled: false to the cluster description for each platform.


Section used for ODCS related configuration.

List of signing intents in their restrictive order. Since composes can be renewed in ODCS, OSBS needs to check if the signing keys used in a compose to be renewed are still valid. If the signing keys are not valid anymore, i.e., keys were removed from the OSBS signing intent definition, OSBS will request ODCS to update the compose signing keys. For OSBS to identify the proper signing intent in such cases, you should not remove signing keys from signing intents. Instead, move the keys that should not be valid anymore from the keys map to the deprecated_keys map in the relevant signing intent definitions. Failing to do so will result in build failures when renewing composes with old signing intent key sets.
Name of the default signing intent to be used when one is not provided in container.yaml.


Define variables that should be propagated to the build environment here. Note that some variables are reserved and defining them will cause an error, e.g. USER_PARAMS, REACTOR_CONFIG.

For example, you might want to set up an HTTP proxy:

- name: HTTP_PROXY
  value: ""
  value: ""
- name: NO_PROXY
  value: localhost,

Limiting image size

You can check the binary image’s size before it is pushed to a registry. If it exceeds the configured size, the built image will not be pushed and the build fails.

A typical configuration in reactor config map looks like:

  binary_image: 10000

The value is the size in bytes of uncompressed layers. When either binary_image or image_size_limit is omitted, or if binary_image is set to 0, the check will be skipped.

Setting up koji for container image builds

Example configuration file: Koji builder

The configuration required for submitting an orchestrator build is different than that required for the orchestrator build itself to submit worker builds. The osbs.conf used by the Koji builder would include:

build_json_dir = /usr/share/osbs/

architecture = amd64

openshift_url =
build_image =

distribution_scope = public

can_orchestrate = true  # allow orchestrator builds

# This secret contains configuration relating to which worker
# clusters to use and what their capacities are:
reactor_config_map = reactorconf

# This secret contains the osbs.conf which atomic-reactor will use
# when creating worker builds
client_config_secret = osbsconf

# These additional secrets are mounted inside the build container
# and referenced by token_file in the build container's osbs.conf
token_secrets =

# and auth options, registries, secrets, etc

openshift_url =
build_image =

reactor_config_map = reactorconf
client_config_secret = osbsconf
token_secrets = workertoken:/var/run/secrets/atomic-reactor/workertoken

# All scratch builds have distribution-scope=private
distribution_scope = private

# This causes koji output not to be configured, and for the low
# priority node selector to be used.
scratch = true

# and auth options, registries, secrets, etc

This shows the configuration required to submit a build to the orchestrator cluster using create_prod_build or create_orchestrator_build.

Also shown is the configuration for scratch builds, which will be identical to regular builds but with “private” distribution scope for built images and with the scratch option enabled.

Example configuration file: inside builder image

The osbs.conf used by the builder image for the orchestrator cluster, and which is contained in the Kubernetes secret named by client_config_secret above, would include:

build_json_dir = /usr/share/osbs/

architecture = amd64

openshift_url =
node_selector.x86_64 =
node_selector.ppc64le =
use_auth = true

# This is the path to the token specified in a token_secrets secret.
token_file =

# The same builder image is used for the orchestrator and worker
# builds, but used with different configuration. It should not
# be specified here.
# build_image =

# and auth options, registries, secrets, etc

openshift_url =
node_selector.x86_64 = none
use_auth = true
token_file =
# and auth options, registries, secrets, etc

In this configuration file there are two worker clusters, one which builds for both x86_64 and ppc64le platforms using nodes with specific labels (prod-mixed), and another which only accepts x86_64 builds (prod-osd).

Including OpenShift build annotations in Koji task output

It is possible to include a build_annotations.json file in the task output of successful container image builds. This file may include any wanted OpenShift build annotations for the container build triggered by the Koji task in question.

The koji-containerbuild plugin looks for a koji_task_annotations_whitelist annotation in the OpenShift build annotations. This key should hold a list of annotations to be whitelisted for inclusion in the build_annotations.json file.

If an empty build_annotations.json file would be generated through the process described above, the file is omitted from the task output. For instance, koji_task_annotations_whitelist could be empty, or the whitelisted annotations not present in OpenShift build annotations.

To whitelist the desired annotations in the koji_task_annotations_whitelist OpenShift annotation described above, you can use the task_annotations_whitelist koji configuration in the reactor_config_map. See Server-side Configuration for atomic-reactor for further reference.

The build_annotations.json file is a JSON object with first level key/values where each key is a whitelisted OpenShift build annotation mapped to it’s value.

Priority of Container Image Builds

For a build system it’s desirable to prioritize different kinds of builds in order to better utilize resources. Unfortunately, OpenShift’s scheduling algorithm does not support setting a priority value for a given build. To achieve some sort of build prioritization, we can leverage node selectors to allocate different resources to different build types.

Consider the following types of container builds:

  • scratch build
  • explicit build
  • auto rebuild

As the name implies, scratch builds are meant to be used as a one-off unofficial container build. No guarantees are made for storing the created container images long term. It’s also not meant to be shipped to customers. These are clearly low priority builds.

Explicit builds are those triggered by a user, either directly via fedpkg/koji CLI, or indirectly via pungi (as in the case of base images). These are official builds that will go through the normal life cycle of being tested and, eventually, shipped.

Auto rebuilds are created by OpenShift when a change in the parent image is detected. It’s likely that layered images should be rebuilt in order to pick up changes in latest parent image.

For any explicit build or auto rebuild, they may or may not be high priority. In some cases, a build is high priority due to a security fix, for instance. In other cases, it could be due to an in-progress feature. For this reason, it cannot be said that all explicit builds are higher priority than auto rebuilds, or vice-versa.

However, auto rebuilds have the potential of completely consuming OSBS’s infrastructure. There must be some mechanism to throttle the amount of auto rebuilds. For this reason, OSBS uses a different node selector for each different build type:

  • scratch build: builds_scratch=true
  • explicit build: builds_explicit=true
  • auto rebuild: builds_auto=true

By controlling each type of builds individually, OSBS will have the necessary control for adjusting its infrastructure.

For example, consider an OpenShift cluster with 5 compute nodes:

Node builds_scratch=true builds_explicit=true builds_auto=true
Node 1
Node 2
Node 3
Node 4
Node 5

In this case, scratch builds can be scheduled only on Node 1; explicit builds on any node except Node 3; and auto builds on any node except Node 2.

Worker Builds Node Selectors

The build type node selectors are only applied to worker builds. This gives more granular control over available resources. Since worker builds are the ones that actually perform the container image building steps, it requires more resources than orchestrator builds. For this reason, a deployment is more likely to have more nodes available for worker builds than orchestrator builds. This is important because the amount of nodes available defines the granularity of how builds are spread across the cluster.

For instance, consider a large deployment in which only 2 orchestrator nodes are needed. If build type node selectors are applied to orchestrator builds, builds can only be throttled by a factor of 2. In contrast, this same deployment may use 20 worker builds, allowing builds to be throttled by a factor of 20.

Orchestrator Builds Allocation

Usually in a deployment, the amount of allowed orchestrator builds matches the amount of allowed worker builds for any given platform. Additional orchestrator builds should be allowed to fully leverage the build type node selectors on worker builds since some orchestrator builds will wait longer than usual for their worker builds to be scheduled. This provides a buffer that allows OpenShift to properly schedule worker builds according to their build type via node selectors. Because OpenShift scheduling is used, worker builds of same type will run in the order they were submitted.

Koji Builder Capacity

The task load of the Koji builders used by OSBS will not reflect the actual load on the OpenShift cluster used by OSBS. The disparity is due to auto rebuilds not having a corresponding Koji task. This creates a scenario where a buildContainer Koji task is started, but the OpenShift build remains in pending state. The Koji builder capacity should be set based on how many nodes allow scratch builds and/or explicit builds. In the example above, there are 4 nodes that allow such builds.

The log file, osbs-client.log, in a Koji task gives users a better understanding of any delays due to scheduling.

Operator manifests

Supporting Operator Manifests extraction

To support the operator manifests extraction, as described in Operator manifests, the operator-manifests BType must be created in koji. This is done by running

koji call addBType operator-manifests

Enabling Operator Manifests digest pinning (and other replacements)

To enable digest pinning and other replacements of image pullspecs for operator manifest bundle builds, atomic-reactor config must include the operator_manifests section. See configuration details in config.json.


    - registry:
    - old:
    - koji_package1
    - koji_package2

List of allowed registries for images before replacement. If any image is found whose registry is not in allowed_registries, build will fail. This key is required.

Should be a subset of source_registry + pull_registries (see config.json).


Each registry may optionally have a “package mapping” - a YAML file that contains a mapping of [package name => list of repos] (see package_mapping.json). The file needs to be uploaded somewhere that OSBS can access, and will be downloaded from there during build if necessary.

Images from registries with a package mapping will have their namespace/repo replaced. OSBS will query the registry to find the package name for the image (determined by the component label) and get the matching replacement from the mapping file. If there is no replacement, or if there is more than one, build will fail and user will have to specify one in container.yaml.

Each registry may optionally have a replacement. After pinning digest and replacing namespace/repo, all old registries in image pullspecs will be replaced by their new replacements.
List of koji packages which are allowed to use skip_all option in the operator_manifests section of container.yaml.

Enabling integration with OMPS service

To enable optional integration with OMPS service to allow automatically pushing operators manifests to application registry (like quay) omps configuration section must be added into atomic-reactor configuration. See configuration details in config.json.


  omps_namespace: organization
  omps_secret: /dir/where/token/file/will/be/mounted

Cachito integration

cachito caches specific versions of upstream projects source code along with dependencies and provides a single tarball with such content for download upon request. This is important when you want track the version of a project and its dependencies in a more robust manner, without handing control of storing and handling the source code for a third party (e.g., if tracking is performed in an external git forge, someone could force push a change to the repository or simply delete it).

OSBS is able to use cachito to handle the source code used to build a container image. The source code archive provided by cachito and the data used to perform the cachito request may then be attached to the koji build output, making it easier to track the components built in a given container image.

This section describes how to configure OSBS to use cachito as described above. Fetching source code from external source using cachito describes how to get OSBS to use cachito in a specific container build, as an OSBS user.

Configuring your cachito instance

To enable cachito integration in OSBS, you must use the cachito configuration in the reactor_config_map. See configuration details in config.json.


    ssl_certs_dir: /dir/with/cert/file

Configuring koji

Adding remote-sources BType

To fully support cachito integration, as described in Cachito integration, the remote-sources BType must be created in koji. This is done by running

koji call addBType remote-sources

This new build type will hold cachito related build artifacts generated in atomic-reactor, which should include a tarball with the upstream source code for the software installed in the container image and a remote-source.json file, which is a JSON representation of the source request sent to cachito by atomic-reactor. This JSON file includes information such as the repository from where cachito downloaded the source code and the revision reference that was downloaded (e.g., a git commit hash).

Whitelisting remote_source_url build annotation

In addition to adding the new BType to koji, you may also want to whitelist the OpenShift remote_source_url build annotation. This is specially useful for scratch builds, where a koji build is not generated and users would not have information about how the sources were fetch for that build easily available. whitelist-annotations describes the steps needed to whitelist OpenShift build annotations.


Builds will automatically cancel themselves if any worker takes more than 3 hours to complete or the entire task takes more than 4 hours to complete. Administrators can override these run time values with the worker_max_run_hours and orchestrator_max_run_hours settings in the osbs.conf file.

Obtaining Atomic Reactor stack trace

atomic-reactor captures SIGUSR1 signals. When receiving such signal, atomic-reactor responds by showing the current stack trace for every thread it was running when the signal was received.

An administrator can use this to inspect the orchestrator or a specific worker build. It is specially useful to diagnose stuck builds.

As an administrator, use podman kill --signal=SIGUSR1 <BUILDROOT_CONTAINER> or podman exec <BUILDROOT_CONTAINER> kill -s SIGUSR1 1 to send the signal to the buildroot container you wish to inspect. atomic-reactor will dump stack traces for all its threads into the buildroot container logs. For instance:

Thread 0x7f6e88a1b700 (most recent call first):
  File "/usr/lib/python2.7/site-packages/atomic_reactor/", line 277, in run
  File "/usr/lib64/python2.7/", line 812, in __bootstrap_inner
  File "/usr/lib64/python2.7/", line 785, in __bootstrap

Current thread 0x7f6e95dbf740 (most recent call first):
  File "/usr/lib/python2.7/site-packages/atomic_reactor/", line 74, in dump_traceback
  File "/usr/lib/python2.7/site-packages/atomic_reactor/", line 1562, in dump_stacktraces
  File "/usr/lib64/python2.7/", line 476, in readline
  File "/usr/lib64/python2.7/", line 620, in _read_chunked
  File "/usr/lib64/python2.7/", line 578, in read
  File "/usr/lib/python2.7/site-packages/urllib3/", line 203, in read
  File "/usr/lib/python2.7/site-packages/docker/", line 247, in _stream_helper
  File "/usr/lib/python2.7/site-packages/atomic_reactor/", line 297, in wait_for_command
  File "/usr/lib/python2.7/site-packages/atomic_reactor/plugins/", line 46, in run
  File "/usr/lib/python2.7/site-packages/atomic_reactor/", line 239, in run
  File "/usr/lib/python2.7/site-packages/atomic_reactor/", line 449, in run
  File "/usr/lib/python2.7/site-packages/atomic_reactor/", line 444, in build_docker_image
  File "/usr/lib/python2.7/site-packages/atomic_reactor/", line 547, in build_inside
  File "/usr/lib/python2.7/site-packages/atomic_reactor/cli/", line 95, in cli_inside_build
  File "/usr/lib/python2.7/site-packages/atomic_reactor/cli/", line 292, in run
  File "/usr/lib/python2.7/site-packages/atomic_reactor/cli/", line 310, in run
  File "/usr/bin/atomic-reactor", line 11, in <module>

In this example, this build is stuck talking to the docker client (docker/