fix(volumes): default to 40 volumes spanning available disk space (#15)

* fix(volumes): increase volume count and decrease size to ensure available volumes for s3 buckets

* env var for controlling maximum storage capacity, calculate volume size within entrypoint

* default storage capacity to filling currently available disk space

cryostat-entrypoint.bash

@@ -47,19 +47,19 @@ done
 
 createBuckets "${names[@]}" &
 
-FLAGS=()
-
-if [ -n "${VOLUME_MAX}" ]; then
-    FLAGS+=("-volume.max=${VOLUME_MAX}")
-fi
-
-if [ -n "${VOLUME_SIZE_LIMIT_MB}" ]; then
-    FLAGS+=("-master.volumeSizeLimitMB=${VOLUME_SIZE_LIMIT_MB}")
-fi
+VOLUME_MIN=40
+NUM_VOLUMES=$(( VOLUME_MAX > VOLUME_MIN ? VOLUME_MAX : VOLUME_MIN ))
+DATA_DIR="${DATA_DIR:-/tmp}"
+AVAILABLE_DISK_BYTES="$(df -P -B1 "${DATA_DIR}" | tail -1 | tr -s ' ' | cut -d' ' -f 4)"
+STORAGE_CAPACITY=${STORAGE_CAPACITY:-${AVAILABLE_DISK_BYTES}}
+STORAGE_CAPACITY_BYTES=$(echo "${STORAGE_CAPACITY}" | numfmt --from=iec --suffix=B | tr -d 'B')
+VOLUME_SIZE_BYTES=$(( "${STORAGE_CAPACITY_BYTES}" / "${NUM_VOLUMES}" ))
 
 exec weed -logtostderr=true server \
-    -dir="${DATA_DIR:-/tmp}" \
+    -dir="${DATA_DIR}" \
+    -volume.max=${NUM_VOLUMES} \
+    -volume.fileSizeLimitMB="${FILE_SIZE_LIMIT_MB:-4096}" \
+    -master.volumeSizeLimitMB="$(( "${VOLUME_SIZE_BYTES}" / 1024 / 1024 ))" \
     -master.volumePreallocate="${VOLUME_PREALLOCATE:-false}" \
-    "${FLAGS[@]}" \
     -s3 -s3.config="${cfg}" \
     "$@"