Advanced Build Operations - Builds | Developer Guide | OpenShift Container Platform 3.5

Setting Build Resources
Setting Maximum Duration
Assigning Builds to Specific Nodes
Chaining Builds

Setting Build Resources

By default, builds are completed by pods using unbound resources, such as memory and CPU. These resources can be limited by specifying resource limits in a project’s default container limits.

You can also limit resource use by specifying resource limits as part of the build configuration. In the following example, each of the resources, cpu, and memory parameters are optional:

apiVersion: "v1"
kind: "BuildConfig"
metadata:
  name: "sample-build"
spec:
  resources:
    limits:
      cpu: "100m" (1)
      memory: "256Mi" (2)

1	`cpu` is in CPU units: `100m` represents 0.1 CPU units (100 * 1e-3).
2	`memory` is in bytes: `256Mi` represents 268435456 bytes (256 * 2 ^ 20).

However, if a quota has been defined for your project, one of the following two items is required:

A resources section set with an explicit requests:
```
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.

Setting Maximum Duration

When defining a BuildConfig, 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.

The following example shows the part of a BuildConfig specifying completionDeadlineSeconds field for 30 minutes:

spec:
  completionDeadlineSeconds: 1800

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.

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` and `key2=value2` labels.

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.

See Configuring Global Build Defaults and Overrides for more information.

If the specified NodeSelector cannot be matched to a node with those labels, the build still stay in the Pending state indefinitely.

Chaining Builds

For compiled languages (Go, C, C++, Java, etc.), 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 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 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 Source-to-Image build and a Docker build, the first build can use any strategy that will produce 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 will depend on the assemble script of the Source-to-Image builder used. In this case, it will be output to /wildfly/standalone/deployments/ROOT.war.

apiVersion: 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
  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: 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 the `artifact-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 need 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.