[librsvg/librsvg-2.42: 1/17] .gitlab-ci.yml: Factor out names of the Docker images, to keep them in a single place

[Federico Mena Quintero <federico src gnome org>]

commit 2010298e74eab2f6b0feac8123f412a7cae21eab
Author: Federico Mena Quintero <federico gnome org>
Date:   Fri Mar 2 08:51:53 2018 -0600

    .gitlab-ci.yml: Factor out names of the Docker images, to keep them in a single place

 .gitlab-ci.yml | 36 ++++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 79a3bf9c..73bedeb3 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,5 +1,17 @@
 # -*- indent-tabs-mode: nil -*-
 
+variables:
+  # Docker images for various distros and architectures
+
+  AMD64_FEDORA_LATEST:       "registry.gitlab.com/alatiera/librsvg-oci-images/amd64/fedora:latest"
+  AMD64_OPENSUSE_TUMBLEWEED: "registry.gitlab.com/alatiera/librsvg-oci-images/amd64/opensuse:tumbleweed"
+  AMD64_DEBIAN_TESTING:      "registry.gitlab.com/alatiera/librsvg-oci-images/amd64/debian:testing"
+
+  I386_DEBIAN_TESTING:       "registry.gitlab.com/alatiera/librsvg-oci-images/i386/debian:testing"
+
+  RUSTFMT_NIGHTLY:           "registry.gitlab.com/alatiera/rustfmt-oci-image/rustfmt:nightly"
+  RUST_NIGHTLY:              "rustlang/rust:nightly"
+
 stages:
   - test
   - lint
@@ -53,14 +65,14 @@ stages:
 ########################################################################
 
 fedora:test:
-  image: registry.gitlab.com/alatiera/librsvg-oci-images/amd64/fedora:latest
+  image: $AMD64_FEDORA_LATEST
   stage: test
   variables:
     LIBRSVG_DEBUG: "yes"
   <<: *distro_test
 
 fedora:test_release:
-  image: registry.gitlab.com/alatiera/librsvg-oci-images/amd64/fedora:latest
+  image: $AMD64_FEDORA_LATEST
   stage: test
   variables:
     LIBRSVG_DEBUG: "no"
@@ -71,7 +83,7 @@ fedora:test_release:
 #######################################################################
 
 fedora:rawhide:
-  image: registry.gitlab.com/alatiera/librsvg-oci-images/amd64/fedora:latest
+  image: $AMD64_FEDORA_LATEST
   stage: cross_distro_amd64
   variables:
     LIBRSVG_DEBUG: "yes"
@@ -84,7 +96,7 @@ fedora:rawhide:
     - web
 
 opensuse:tumbleweed:
-  image: registry.gitlab.com/alatiera/librsvg-oci-images/amd64/opensuse:tumbleweed
+  image: $AMD64_OPENSUSE_TUMBLEWEED
   stage: cross_distro_amd64
   variables:
     LIBRSVG_DEBUG: "yes"
@@ -97,7 +109,7 @@ opensuse:tumbleweed:
     - web
 
 debian:testing:
-  image: registry.gitlab.com/alatiera/librsvg-oci-images/amd64/debian:testing
+  image: $AMD64_DEBIAN_TESTING
   stage: cross_distro_amd64
   variables:
     LIBRSVG_DEBUG: "yes"
@@ -127,7 +139,7 @@ debian:testing:
 #######################################################################
 
 fedora:rawhide_release:
-  image: registry.gitlab.com/alatiera/librsvg-oci-images/amd64/fedora:latest
+  image: $AMD64_FEDORA_LATEST
   stage: cross_distro_amd64
   variables:
     LIBRSVG_DEBUG: "no"
@@ -139,7 +151,7 @@ fedora:rawhide_release:
     - web
 
 opensuse:tumbleweed_release:
-  image: registry.gitlab.com/alatiera/librsvg-oci-images/amd64/opensuse:tumbleweed
+  image: $AMD64_OPENSUSE_TUMBLEWEED
   stage: cross_distro_amd64
   variables:
     LIBRSVG_DEBUG: "no"
@@ -151,7 +163,7 @@ opensuse:tumbleweed_release:
     - web
 
 debian:testing_release:
-  image: registry.gitlab.com/alatiera/librsvg-oci-images/amd64/debian:testing
+  image: $AMD64_DEBIAN_TESTING
   stage: cross_distro_amd64
   variables:
     LIBRSVG_DEBUG: "no"
@@ -166,7 +178,7 @@ debian:testing_release:
 #######################################################################
 
 debian:testing_i386:
-  image: registry.gitlab.com/alatiera/librsvg-oci-images/i386/debian:testing
+  image: $I386_DEBIAN_TESTING
   stage: cross_distro_i386
   variables:
     LIBRSVG_DEBUG: "yes"
@@ -182,7 +194,7 @@ debian:testing_i386:
 #######################################################################
 
 debian:testing_release_i386:
-  image: registry.gitlab.com/alatiera/librsvg-oci-images/i386/debian:testing
+  image: $I386_DEBIAN_TESTING
   stage: cross_distro_i386
   variables:
     LIBRSVG_DEBUG: "no"
@@ -199,7 +211,7 @@ debian:testing_release_i386:
 # Configure and run rustfmt on nightly
 # Exits and builds fails if on bad format
 rustfmt:
-  image: "rustlang/rust:nightly"
+  image: $RUSTFMT_NIGHTLY
   stage: lint
   variables:
     CFG_RELEASE_CHANNEL: "nightly"
@@ -213,7 +225,7 @@ rustfmt:
 # Configure and run clippy on nightly
 # Only fails on errors atm.
 clippy:
-  image: "rustlang/rust:nightly"
+  image: $RUST_NIGHTLY
   stage: lint
   before_script:
     - apt update -yqq