ci: Use newer curl version with exponential backoff

.travis.yml

@@ -18,8 +18,8 @@ before_script:
  # Build images
  - docker-compose build
 
- # Pull buildpack image (curl 7.52.0+)
- - docker pull buildpack-deps:artful-curl
+ # Pull curl image (curl 7.52.0+)
+ - docker pull curlimages/curl
 
 script:
  # Compose

.travis/run-tests.sh

@@ -4,7 +4,7 @@ set -eu
 set -o pipefail
 
 shopt -s expand_aliases
-alias curl="docker run --rm --net=host buildpack-deps:artful-curl curl -s -w '\n'"
+alias curl="docker run --rm --net=host curlimages/curl -s -w '\n'"
 
 function log {
  echo -e "\n[+] $1\n"
@@ -13,20 +13,17 @@ function log {
 log 'Waiting for Elasticsearch readiness'
 curl -D- 'http:https://localhost:9200/' \
  --retry 10 \
- --retry-delay 5 \
  --retry-connrefused \
  -u kibanaserver:kibanaserver
 
 log 'Waiting for Kibana readiness'
 curl -D- 'http:https://localhost:5601/api/status' \
  --retry 10 \
- --retry-delay 5 \
  --retry-connrefused
 
 log 'Waiting for Logstash readiness'
 curl -D- 'http:https://localhost:9600/_node/pipelines/main?pretty' \
  --retry 10 \
- --retry-delay 5 \
  --retry-connrefused
 
 log 'Creating Logstash index pattern in Kibana'