Adding optional override for the agent download url (#12)

* Giving customers the option to override the download url used to download the agent. If SIGSCI_INTERNAL_AGENT_DOWNLOAD_URL is set, use the value for the url. * - fix bad download url - remove extra fi * add note on env var relationships. Co-authored-by: bbucher-sigsci <[email protected]>
signalsciences · Jun 30, 2021 · c797438 · c797438
1 parent 43779ac
commit c797438
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Showing 2 changed files with 35 additions and 21 deletions.
diff --git a/README.md b/README.md
@@ -45,6 +45,10 @@ To configure the Signal Sciences agent the following environment variables must
 
 `SIGSCI_SERVER_HOSTNAME` (optional)
 
+`SIGSCI_AGENT_DOWNLOAD_URL` (optional, NOTE: This needs to be a fully qualified http(s) path to a tar, gzipped agent file)
+
+**_NOTE: If SIGSCI_AGENT_DOWNLOAD_URL is set, then SIGSCI_AGENT_VERSION will be ignored, and SIGSCI_DISABLE_CHECKSUM_INTEGRITY_CHECK will be implied._**
+
 Set environment variables using the `cf` command:
 
 `cf set-env YOUR-APP <variable name> "<value>"`

diff --git a/lib/sigsci-agent.sh b/lib/sigsci-agent.sh
@@ -87,38 +87,49 @@ then
 
   ## install agent
 
-  # if agent version not specified then get the latest version.
-  if [ -z $SIGSCI_AGENT_VERSION ]
+  # if a specific download url is provided, we can bypass version-determination logic
+  if [ -z $SIGSCI_AGENT_DOWNLOAD_URL ]
   then
-    SIGSCI_AGENT_VERSION=$(curl -s -L --retry 45 --retry-delay 2 https://dl.signalsciences.net/sigsci-agent/VERSION)
-  fi
-
-  # check if version exists.
-  STATUS=$(curl -s --retry 45 --retry-delay 2 -o /dev/null -w "%{http_code}" https://dl.signalsciences.net/sigsci-agent/${SIGSCI_AGENT_VERSION}/VERSION)
-  if [ $STATUS -ne 200 ]
-  then
-
-    # if we don't get a 200 response, skip agent installation.
-    (>&2 echo "-----> SigSci Agent version ${SIGSCI_AGENT_VERSION} not found or network unavailable after 90 seconds!")
-    (>&2 echo "-----> SIGSCI AGENT WILL NOT BE INSTALLED!")
+    # if agent version not specified then get the latest version.
+    if [ -z $SIGSCI_AGENT_VERSION ]
+    then
+      SIGSCI_AGENT_VERSION=$(curl -s -L --retry 45 --retry-delay 2 "https://dl.signalsciences.net/sigsci-agent/VERSION")
+    fi
 
-  else
-    echo "-----> Downloading sigsci-agent"
-    curl -s --retry 45 --retry-delay 2 -o sigsci-agent_${SIGSCI_AGENT_VERSION}.tar.gz https://dl.signalsciences.net/sigsci-agent/${SIGSCI_AGENT_VERSION}/linux/sigsci-agent_${SIGSCI_AGENT_VERSION}.tar.gz > /dev/null
+    # check if version exists.
+    STATUS=$(curl -s --retry 45 --retry-delay 2 -o /dev/null -w "%{http_code}" "https://dl.signalsciences.net/sigsci-agent/${SIGSCI_AGENT_VERSION}/VERSION")
 
-    if [ -z $SIGSCI_DISABLE_CHECKSUM_INTEGRITY_CHECK ]
+    if [ $STATUS -ne 200 ]
     then
-        curl -s --retry 45 --retry-delay 2 -o sigsci-agent_${SIGSCI_AGENT_VERSION}.tar.gz.sha256 https://dl.signalsciences.net/sigsci-agent/${SIGSCI_AGENT_VERSION}/linux/sigsci-agent_${SIGSCI_AGENT_VERSION}.tar.gz.sha256 > /dev/null
+      # if we don't get a 200 response, skip agent installation.
+      (>&2 echo "-----> SigSci Agent version ${SIGSCI_AGENT_VERSION} not found or network unavailable after 90 seconds!")
+      (>&2 echo "-----> SIGSCI AGENT WILL NOT BE INSTALLED!")
+    else
+      echo "-----> Downloading sigsci-agent"
+      curl -s --retry 45 --retry-delay 2 -o sigsci-agent_${SIGSCI_AGENT_VERSION}.tar.gz "https://dl.signalsciences.net/sigsci-agent/${SIGSCI_AGENT_VERSION}/linux/sigsci-agent_${SIGSCI_AGENT_VERSION}.tar.gz" > /dev/null
+
+      if [ -z $SIGSCI_DISABLE_CHECKSUM_INTEGRITY_CHECK ]
+      then
+        curl -s --retry 45 --retry-delay 2 -o sigsci-agent_${SIGSCI_AGENT_VERSION}.tar.gz.sha256 "https://dl.signalsciences.net/sigsci-agent/${SIGSCI_AGENT_VERSION}/linux/sigsci-agent_${SIGSCI_AGENT_VERSION}.tar.gz.sha256" > /dev/null
 
         # validate the gzip file
         if [[ "$(shasum -c sigsci-agent_${SIGSCI_AGENT_VERSION}.tar.gz.sha256)" != *"OK"* ]]
         then
             (>&2 echo "-----> sigsci-agent not installed because checksum integrity check failed")
             exit 1
+        else
+          # shasum expects to find the agent tar.gz file with the version in the name. Rename the file if shasum check passes so that the name is consistent regardless of where the file was downloaded from
+          mv sigsci-agent_${SIGSCI_AGENT_VERSION}.tar.gz sigsci-agent.tar.gz
         fi
+      fi
+    fi
+    else
+      # download the agent tar.gz from a custom url
+      echo "-----> Downloading SigSci Agent from ${SIGSCI_AGENT_DOWNLOAD_URL}"
+      curl -s --retry 45 --retry-delay 2 -o sigsci-agent.tar.gz $SIGSCI_AGENT_DOWNLOAD_URL > /dev/null
     fi
 
-    tar -xzf "sigsci-agent_${SIGSCI_AGENT_VERSION}.tar.gz"
+    tar -xzf "sigsci-agent.tar.gz"
     mv sigsci-agent "${SIGSCI_DIR}/bin/sigsci-agent"
     echo "-----> Finished installing sigsci-agent"
 
@@ -237,11 +248,10 @@ EOT
         health_check &
       fi
     fi
-  fi
 
 else
   (>&2 echo "-----> Signal Sciences access keys not set. Agent not starting!!!")
   (>&2 echo "-----> To enable the Signal Sciences agent please set the following environment variables:")
   (>&2 echo "-----> SIGSCI_ACCESSKEYID")
   (>&2 echo "-----> SIGSCI_SECRETACCESSKEY")
-fi
+fi