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Chapter 9. Performing advanced builds
The following sections provide instructions for advanced build operations including setting build resources and maximum duration, assigning builds to nodes, chaining builds, build pruning, and build run policies.
9.1. Setting build resources
By default, builds are completed by pods using unbound resources, such as memory and CPU. These resources can be limited.
Procedure
You can limit resource use in two ways:
- Limit resource use by specifying resource limits in the default container limits of a project.
Limit resource use by specifying resource limits as part of the build configuration. ** In the following example, each of the
resources
,cpu
, andmemory
parameters are optional:apiVersion: "v1" kind: "BuildConfig" metadata: name: "sample-build" spec: resources: limits: cpu: "100m" 1 memory: "256Mi" 2
However, if a quota has been defined for your project, one of the following two items is required:
A
resources
section set with an explicitrequests
:resources: requests: 1 cpu: "100m" memory: "256Mi"
- 1
- The
requests
object contains the list of resources that correspond to the list of resources in the quota.
A limit range defined in your project, where the defaults from the
LimitRange
object apply to pods created during the build process.Otherwise, build pod creation will fail, citing a failure to satisfy quota.
9.2. Setting maximum duration
When defining a BuildConfig
object, you can define its maximum duration by setting the completionDeadlineSeconds
field. It is specified in seconds and is not set by default. When not set, there is no maximum duration enforced.
The maximum duration is counted from the time when a build pod gets scheduled in the system, and defines how long it can be active, including the time needed to pull the builder image. After reaching the specified timeout, the build is terminated by OpenShift Container Platform.
Procedure
To set maximum duration, specify
completionDeadlineSeconds
in yourBuildConfig
. The following example shows the part of aBuildConfig
specifyingcompletionDeadlineSeconds
field for 30 minutes:spec: completionDeadlineSeconds: 1800
This setting is not supported with the Pipeline Strategy option.
9.3. Assigning builds to specific nodes
Builds can be targeted to run on specific nodes by specifying labels in the nodeSelector
field of a build configuration. The nodeSelector
value is a set of key-value pairs that are matched to Node
labels when scheduling the build pod.
The nodeSelector
value can also be controlled by cluster-wide default and override values. Defaults will only be applied if the build configuration does not define any key-value pairs for the nodeSelector
and also does not define an explicitly empty map value of nodeSelector:{}
. Override values will replace values in the build configuration on a key by key basis.
If the specified NodeSelector
cannot be matched to a node with those labels, the build still stay in the Pending
state indefinitely.
Procedure
Assign builds to run on specific nodes by assigning labels in the
nodeSelector
field of theBuildConfig
, for example:apiVersion: "v1" kind: "BuildConfig" metadata: name: "sample-build" spec: nodeSelector:1 key1: value1 key2: value2
- 1
- Builds associated with this build configuration will run only on nodes with the
key1=value2
andkey2=value2
labels.
9.4. Chained builds
For compiled languages such as Go, C, C++, and Java, including the dependencies necessary for compilation in the application image might increase the size of the image or introduce vulnerabilities that can be exploited.
To avoid these problems, two builds can be chained together. One build that produces the compiled artifact, and a second build that places that artifact in a separate image that runs the artifact.
In the following example, a source-to-image (S2I) build is combined with a docker build to compile an artifact that is then placed in a separate runtime image.
Although this example chains a S2I build and a docker build, the first build can use any strategy that produces an image containing the desired artifacts, and the second build can use any strategy that can consume input content from an image.
The first build takes the application source and produces an image containing a WAR
file. The image is pushed to the artifact-image
image stream. The path of the output artifact depends on the assemble
script of the S2I builder used. In this case, it is output to /wildfly/standalone/deployments/ROOT.war
.
apiVersion: build.openshift.io/v1 kind: BuildConfig metadata: name: artifact-build spec: output: to: kind: ImageStreamTag name: artifact-image:latest source: git: uri: https://github.com/openshift/openshift-jee-sample.git ref: "master" strategy: sourceStrategy: from: kind: ImageStreamTag name: wildfly:10.1 namespace: openshift
The second build uses image source with a path to the WAR file inside the output image from the first build. An inline dockerfile
copies that WAR
file into a runtime image.
apiVersion: build.openshift.io/v1 kind: BuildConfig metadata: name: image-build spec: output: to: kind: ImageStreamTag name: image-build:latest source: dockerfile: |- FROM jee-runtime:latest COPY ROOT.war /deployments/ROOT.war images: - from: 1 kind: ImageStreamTag name: artifact-image:latest paths: 2 - sourcePath: /wildfly/standalone/deployments/ROOT.war destinationDir: "." strategy: dockerStrategy: from: 3 kind: ImageStreamTag name: jee-runtime:latest triggers: - imageChange: {} type: ImageChange
- 1
from
specifies that the docker build should include the output of the image from theartifact-image
image stream, which was the target of the previous build.- 2
paths
specifies which paths from the target image to include in the current docker build.- 3
- The runtime image is used as the source image for the docker build.
The result of this setup is that the output image of the second build does not have to contain any of the build tools that are needed to create the WAR
file. Also, because the second build contains an image change trigger, whenever the first build is run and produces a new image with the binary artifact, the second build is automatically triggered to produce a runtime image that contains that artifact. Therefore, both builds behave as a single build with two stages.
9.5. Pruning builds
By default, builds that have completed their lifecycle are persisted indefinitely. You can limit the number of previous builds that are retained.
Procedure
Limit the number of previous builds that are retained by supplying a positive integer value for
successfulBuildsHistoryLimit
orfailedBuildsHistoryLimit
in yourBuildConfig
, for example:apiVersion: "v1" kind: "BuildConfig" metadata: name: "sample-build" spec: successfulBuildsHistoryLimit: 2 1 failedBuildsHistoryLimit: 2 2
Trigger build pruning by one of the following actions:
- Updating a build configuration.
- Waiting for a build to complete its lifecycle.
Builds are sorted by their creation timestamp with the oldest builds being pruned first.
Administrators can manually prune builds using the 'oc adm' object pruning command.
9.6. Build run policy
The build run policy describes the order in which the builds created from the build configuration should run. This can be done by changing the value of the runPolicy
field in the spec
section of the Build
specification.
It is also possible to change the runPolicy
value for existing build configurations, by:
-
Changing
Parallel
toSerial
orSerialLatestOnly
and triggering a new build from this configuration causes the new build to wait until all parallel builds complete as the serial build can only run alone. -
Changing
Serial
toSerialLatestOnly
and triggering a new build causes cancellation of all existing builds in queue, except the currently running build and the most recently created build. The newest build runs next.