Don't make iomonitor so aggressive; just warn about scenario instead

Author: hach-que

BASIC-CONFIG.md

@@ -17,8 +17,6 @@ docker run ... \
     ...
 ```
 
-Note that the environment variable's value is equal to the linked container's name once converted to the variable format; that is a linked container name of `my.sql.container` would become `MY_SQL_CONTAINER`.
-
 If your instance of MySQL is running on the host or some external system, you can connect to it using the `MYSQL_USER` and associated variables like so:
 
 ```

ENV-LIST.md

@@ -11,7 +11,6 @@
 - `PHABRICATOR_HOST_KEYS_PATH` - The path to store SSH host keys in.  This directory should be a volume mapped from the host, otherwise clients will be unable to connect after the container is restarted.
 - `AWS_S3_ACCESS_KEY` - The AWS access key to use for S3.  Only needed when the `s3` storage type is selected.
 - `AWS_S3_SECRET_KEY` - The AWS secret key to use for S3.  Only needed when the `s3` storage type is selected.
-- `MYSQL_LINKED_CONTAINER` - Use this if you want to connect to a MySQL container (see [Basic Configuration](BASIC-CONFIG.md)).
 - `MYSQL_HOST` - Use this if you want to connect to an external MySQL host (see [Basic Configuration](BASIC-CONFIG.md)).
 - `MYSQL_PORT` - When connecting to an external MySQL host, use this port (optional).
 - `MYSQL_USER` - The user to connect to MySQL as.
@@ -23,6 +22,7 @@
 - `SSL_CERTIFICATE` - The path to the SSL certificate chain (manual mode only).
 - `SSL_PRIVATE_KEY` - The path to the SSL private key (manual mode only).
 - `SSL_EMAIL` - The email address to use when registering for an SSL certificate (Let's Encrypt mode only)
+- `DISABLE_IOMONITOR` - Disable the I/O monitor, which warns if the image is spending a lot of CPU time waiting on disk I/O.
 
 The following advanced options automatically turn on `ENABLE_UPDATE_ON_START`:
 

iomonitor

@@ -3,9 +3,7 @@
 # Occasionally parsing Git diffs may consume all disk I/O
 # on a server, impacting other services including the web
 # front-end.  This script monitors disk I/O and automatically
-# kills Git processes whenever the CPU has been waiting on
-# the disk for more than 50% of the CPU time in the last
-# 60 seconds.
+# warns the server administrator in the output log.
 
 while [ 0 -eq 0 ]; do
   RESULTS=$(top -b -n 2 -d 60 | awk '/[0-9.]\ wa,/{print $10}')
@@ -15,8 +13,7 @@ while [ 0 -eq 0 ]; do
   done
 
   if echo $LAST_RESULT 50 | awk '{exit $1>$2?0:1}'; then
-    echo "[iomonitor] Detected >50% CPU waiting on disk; automatically killing Git processes..."
-    kill -KILL $(pidof git)
+    echo "[iomonitor] Warning: detected >50% CPU waiting on disk.  Consider increasing disk performance or using --cpu-quota to constrain Docker CPU usage."
   fi
 
   sleep 2