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Posted to commits@druid.apache.org by GitBox <gi...@apache.org> on 2021/03/09 00:14:38 UTC
[GitHub] [druid] himanshug opened a new pull request #10961: k8s discovery module: fix issue for druid.host being more than 63chars not permitted as k8s resource label value
himanshug opened a new pull request #10961:
URL: https://github.com/apache/druid/pull/10961
### Description
Fixes a bug which shows up in specific deployments, that use k8s based discovery module, where `druid.host` gets set to something more than 63 characters which is the max length limit on kubernetes label values.
Currently we put full `host:port` as a k8s label inside pod spec, which can be of arbitrary length. This patch changes node discovery mechanism to work with a hash of `host:port` in the label value instead.
It is the (2) issue described in https://github.com/apache/druid/issues/10752#issuecomment-760547707 . Since this issue will be encountered by users quickly so hoping to have this included in 0.21.0 release.
PS: Existing [unit/integration] tests cover the changes made here. It would further be exercised in a larger PR that introduces leader election improvements and integration tests similar to https://github.com/apache/druid/pull/10680 would be done later, that is blocked on a new release from kubernetes java client lib we use, that contains few leader election algorithm improvements.
<hr>
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This PR has:
- [x] been self-reviewed.
- [ ] using the [concurrency checklist](https://github.com/apache/druid/blob/master/dev/code-review/concurrency.md) (Remove this item if the PR doesn't have any relation to concurrency.)
- [x] added documentation for new or modified features or behaviors.
- [x] added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
- [ ] added or updated version, license, or notice information in [licenses.yaml](https://github.com/apache/druid/blob/master/dev/license.md)
- [ ] added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
- [x] added unit tests or modified existing tests to cover new code paths, ensuring the threshold for [code coverage](https://github.com/apache/druid/blob/master/dev/code-review/code-coverage.md) is met.
- [ ] added integration tests.
- [ ] been tested in a test Druid cluster.
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[GitHub] [druid] jihoonson merged pull request #10961: k8s discovery module: fix issue for druid.host being more than 63chars not permitted as k8s resource label value
Posted by GitBox <gi...@apache.org>.
jihoonson merged pull request #10961:
URL: https://github.com/apache/druid/pull/10961
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[GitHub] [druid] zhangyue19921010 commented on a change in pull request #10961: k8s discovery module: fix issue for druid.host being more than 63chars not permitted as k8s resource label value
Posted by GitBox <gi...@apache.org>.
zhangyue19921010 commented on a change in pull request #10961:
URL: https://github.com/apache/druid/pull/10961#discussion_r589916239
##########
File path: extensions-core/kubernetes-extensions/src/main/java/org/apache/druid/k8s/discovery/K8sDruidNodeAnnouncer.java
##########
@@ -237,30 +236,14 @@ private String getPodDefAnnocationPath(String annotation)
return StringUtils.format("%s/%s", POD_ANNOTATIONS_PATH_PREFIX, annotation);
}
- private static String encodeHostPort(String hostPort)
+ // a valid label must be an empty string or consist of alphanumeric characters, '-', '_' or '.', and
+ // must start and end with an alphanumeric character
+ private static String hashEncodeStringForLabelValue(String str)
{
- //K8S requires that label values must match regex (([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9])?
- //So, it is essential to replace ':' with '-'
-
- // it is assumed that hostname does not have ':' in it except for separating host and port
- Preconditions.checkState(
- hostPort.indexOf(':') == hostPort.lastIndexOf(':'),
- "hostname in host:port[%s] has ':' in it", hostPort
- );
-
- return hostPort.replace(':', '-');
- }
-
- private String replaceLast(String str, char oldChar, char newChar)
- {
- char[] chars = str.toCharArray();
- for (int i = chars.length - 1; i >= 0; i--) {
- if (chars[i] == oldChar) {
- chars[i] = newChar;
- break;
- }
+ int hash = str.hashCode();
+ if (hash < 0) {
+ hash = -1 * hash;
Review comment:
nit: Just wondering if this is a best way to solve 63chars limitation using `String.hascode()`. As we know, String.hashCode() isn't unique, but it can't be(https://sigpwned.com/2018/08/10/string-hashcode-is-plenty-unique/). And `hash = -1 * hash` will double the probability of conflict.
In other words, what happens if there is a conflict? Does the conflict will lead to a wrong SelfDiscovery? If not, I think `String.hascode()` is good enough.
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[GitHub] [druid] himanshug commented on a change in pull request #10961: k8s discovery module: fix issue for druid.host being more than 63chars not permitted as k8s resource label value
Posted by GitBox <gi...@apache.org>.
himanshug commented on a change in pull request #10961:
URL: https://github.com/apache/druid/pull/10961#discussion_r589977445
##########
File path: extensions-core/kubernetes-extensions/src/main/java/org/apache/druid/k8s/discovery/K8sDruidNodeAnnouncer.java
##########
@@ -237,30 +236,14 @@ private String getPodDefAnnocationPath(String annotation)
return StringUtils.format("%s/%s", POD_ANNOTATIONS_PATH_PREFIX, annotation);
}
- private static String encodeHostPort(String hostPort)
+ // a valid label must be an empty string or consist of alphanumeric characters, '-', '_' or '.', and
+ // must start and end with an alphanumeric character
+ private static String hashEncodeStringForLabelValue(String str)
{
- //K8S requires that label values must match regex (([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9])?
- //So, it is essential to replace ':' with '-'
-
- // it is assumed that hostname does not have ':' in it except for separating host and port
- Preconditions.checkState(
- hostPort.indexOf(':') == hostPort.lastIndexOf(':'),
- "hostname in host:port[%s] has ':' in it", hostPort
- );
-
- return hostPort.replace(':', '-');
- }
-
- private String replaceLast(String str, char oldChar, char newChar)
- {
- char[] chars = str.toCharArray();
- for (int i = chars.length - 1; i >= 0; i--) {
- if (chars[i] == oldChar) {
- chars[i] = newChar;
- break;
- }
+ int hash = str.hashCode();
+ if (hash < 0) {
+ hash = -1 * hash;
Review comment:
hash collision here has no impact on correctness , this is only used to get a suitable list of candidates. and, this is only used for finding a specific node by host:port for the health check.
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[GitHub] [druid] zhangyue19921010 commented on a change in pull request #10961: k8s discovery module: fix issue for druid.host being more than 63chars not permitted as k8s resource label value
Posted by GitBox <gi...@apache.org>.
zhangyue19921010 commented on a change in pull request #10961:
URL: https://github.com/apache/druid/pull/10961#discussion_r589916239
##########
File path: extensions-core/kubernetes-extensions/src/main/java/org/apache/druid/k8s/discovery/K8sDruidNodeAnnouncer.java
##########
@@ -237,30 +236,14 @@ private String getPodDefAnnocationPath(String annotation)
return StringUtils.format("%s/%s", POD_ANNOTATIONS_PATH_PREFIX, annotation);
}
- private static String encodeHostPort(String hostPort)
+ // a valid label must be an empty string or consist of alphanumeric characters, '-', '_' or '.', and
+ // must start and end with an alphanumeric character
+ private static String hashEncodeStringForLabelValue(String str)
{
- //K8S requires that label values must match regex (([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9])?
- //So, it is essential to replace ':' with '-'
-
- // it is assumed that hostname does not have ':' in it except for separating host and port
- Preconditions.checkState(
- hostPort.indexOf(':') == hostPort.lastIndexOf(':'),
- "hostname in host:port[%s] has ':' in it", hostPort
- );
-
- return hostPort.replace(':', '-');
- }
-
- private String replaceLast(String str, char oldChar, char newChar)
- {
- char[] chars = str.toCharArray();
- for (int i = chars.length - 1; i >= 0; i--) {
- if (chars[i] == oldChar) {
- chars[i] = newChar;
- break;
- }
+ int hash = str.hashCode();
+ if (hash < 0) {
+ hash = -1 * hash;
Review comment:
nit: Just wondering if this is a best way to solve 63chars limitation using `String.hascode()`. As we know, String.hashCode() isn't unique, but it can't be(https://sigpwned.com/2018/08/10/string-hashcode-is-plenty-unique/). And `hash = -1 * hash` will double the probability of conflict.
In other words, what will happen if there is a conflict? Does the conflict will lead to a wrong SelfDiscovery? If not, I think `String.hascode()` is good enough.
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[GitHub] [druid] zhangyue19921010 commented on a change in pull request #10961: k8s discovery module: fix issue for druid.host being more than 63chars not permitted as k8s resource label value
Posted by GitBox <gi...@apache.org>.
zhangyue19921010 commented on a change in pull request #10961:
URL: https://github.com/apache/druid/pull/10961#discussion_r589981198
##########
File path: extensions-core/kubernetes-extensions/src/main/java/org/apache/druid/k8s/discovery/K8sDruidNodeAnnouncer.java
##########
@@ -237,30 +236,14 @@ private String getPodDefAnnocationPath(String annotation)
return StringUtils.format("%s/%s", POD_ANNOTATIONS_PATH_PREFIX, annotation);
}
- private static String encodeHostPort(String hostPort)
+ // a valid label must be an empty string or consist of alphanumeric characters, '-', '_' or '.', and
+ // must start and end with an alphanumeric character
+ private static String hashEncodeStringForLabelValue(String str)
{
- //K8S requires that label values must match regex (([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9])?
- //So, it is essential to replace ':' with '-'
-
- // it is assumed that hostname does not have ':' in it except for separating host and port
- Preconditions.checkState(
- hostPort.indexOf(':') == hostPort.lastIndexOf(':'),
- "hostname in host:port[%s] has ':' in it", hostPort
- );
-
- return hostPort.replace(':', '-');
- }
-
- private String replaceLast(String str, char oldChar, char newChar)
- {
- char[] chars = str.toCharArray();
- for (int i = chars.length - 1; i >= 0; i--) {
- if (chars[i] == oldChar) {
- chars[i] = newChar;
- break;
- }
+ int hash = str.hashCode();
+ if (hash < 0) {
+ hash = -1 * hash;
Review comment:
Thanks for your explanation :)
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