task runtime: add default ":latest" tag to docker image if none prese…

…nt (#246)

see also issue #232

.travis.yml

@@ -1,9 +1,11 @@
-language: cpp
+language: python
 dist: bionic
+services:
+  - docker
 
 script:
   - |
-      set -ex -o pipefail
+      set -exo pipefail
       make docker
       docker run --env TRAVIS_JOB_ID=${TRAVIS_JOB_ID} --env TRAVIS_BRANCH=${TRAVIS_BRANCH} \
                  -v /var/run/docker.sock:/var/run/docker.sock -v /tmp:/tmp \

WDL/runtime/task.py

@@ -235,6 +235,9 @@ def _run(self, logger: logging.Logger, command: str) -> int:
             stderr_file = os.path.join(self.host_dir, "stderr.txt")
             pygtail = Pygtail(stderr_file, full_lines=True)
             pygtail_exn = False
+            if ":" not in self.image_tag:
+                # seems we need to do this explicitly under some configurations -- issue #232
+                self.image_tag += ":latest"
             try:
                 # run container
                 logger.info("docker starting image {}".format(self.image_tag))

tests/test_4taskrun.py

@@ -95,6 +95,23 @@ def test_docker(self):
         }
         """, expected_exception=docker.errors.ImageNotFound)
 
+        # issue #232
+        outputs = self._test_task(R"""
+        version 1.0
+        task hello {
+            command <<<
+                cat /etc/issue
+            >>>
+            output {
+                String issue = read_string(stdout())
+            }
+            runtime {
+                docker: "frolvlad/alpine-bash"
+            }
+        }
+        """)
+        self.assertTrue("Alpine Linux" in outputs["issue"])
+
     @log_capture()
     def test_logging_std_err(self, capture):
         self._test_task(R"""