Add PullSecret and update PushSecret and SourceSecret documentation

architecture/core_objects/builds.adoc

@@ -98,12 +98,13 @@ leverage for your applications.
 Custom builds are the most sophisticated version of builds, allowing developers to define a builder image which is responsible for the entire process of the build. The custom builder image is a plain Docker image within which the author embeds the logic of the desired build process, such as building RPMs or building
 base Docker images.
 
-[#using-docker-credentials-for-pushing-images]
-== Using Docker Credentials for Pushing Images
+[#using-docker-credentials-for-pushing-and-pulling-images]
+== Using Docker Credentials for Pushing and Pulling Images
 
-In case you want to push the output image into private Docker registry that
-requires authentication or Docker Hub, you must supply a `.dockercfg` file
-with valid Docker registry credentials.
+In case you want to push the output image into a private Docker Registry or pull
+the builder image from the private Docker Registry that requires authentication
+or Docker Hub, you have to supply the `.dockercfg` file with valid Docker
+Registry credentials.
 
 The *_.dockercfg_* JSON file usually exists in your home directory and has
 following format:
@@ -163,10 +164,43 @@ $ osc create -f secret.json
 ----
 ====
 
-Once you have the `*Secret*` created, you can add a `PushSecretName` field into
+Once you have the `*Secret*` created, you can add a `PushSecret` field into
 `Output` section inside the `BuildConfig` and set it to the name of the
 `*Secret*` that you created, in this case `*dockerhub*`.
 
+```
+"parameters": {
+  "output": {
+    "to": {
+      "name": "private-image"
+    },
+    "pushSecret":{
+      "name":"dockerhub"
+    }
+  }
+}
+```
+
+For pulling the builder Docker image from a private Docker registry, you have to specify
+the `PullSecret` field, which is part of the build strategy definition:
+
+```
+{
+  "strategy": {
+    "stiStrategy": {
+      "from": {
+        "kind": "DockerImage",
+        "name": "docker.io/user/private_repository"
+       },
+       "pullSecret": {
+        "name": "dockerhub"
+       },
+    },
+    "type": "STI"
+  }
+}
+```
+
 [#using-private-repositories-for-builds]
 == Using private repositories for builds
 
@@ -233,7 +267,7 @@ $ osc create -f secret.json
 ----
 ====
 
-Once you have the `*Secret*` created, you can add a `SourceSecretName` field into
+Once you have the `*Secret*` created, you can add a `SourceSecret` field into
 `Source` section inside the `BuildConfig` and set it to the name of the
 `*Secret*` that you created, in this case `*scmsecret*`:
 
@@ -256,7 +290,9 @@ Once you have the `*Secret*` created, you can add a `SourceSecretName` field int
       "git": {
         "uri": "git@repository.com:user/app.git"
       },
-      "sourceSecretName": "scmsecret",
+      "sourceSecret": {
+        "name": "scmsecret"
+      },
       "type": "Git"
     },
     "strategy": {