Thanks.
This is a bit above my present knowledge. So I’ll need some time on that.
I have another approach to look for the cause of the problem.
Before I had finished the binding, I’ve create rule to do fetch the prices (My poste rule).
You could try this rule as well and look if that runs through.
The rule does also use the httpUtil (as did the bindings you tested), that way you are testing if the problem might be the https call (WeatherUnderground is http!).
Yes, I’m fishing in the blind!
The last reported problem is further discussed in here.
Anyone who has further problems/request regarding the Tankerkoenig binding is asked to start a new thread!
My problem discussed here in the lines above and in the separate thread is solved, after usage the latest java version from oracle, available for my RaspPi.
But there is an existing problem with the 2.1.0-binding, if the response JSON contains a NULL value instead a price. In this case you have to switch to the snapshot version 2.2.
A big thanks fly out to @opus and @martinvw for the support, hints and patience with me.
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Hi Dennis,
thank you for your binding.
Actually I have some problem to get it run.
My openhab2 runs on a raspberry pi with based on debian 8.
Now I had connection-problems based on SSL-Errors.
PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
I read your FAQ and installed the startssl-certs but it didn’t work.
But now I noticed, that tankerkoenig now uses Let’s Encrypt
And that was my problem:
In the default repo there is only JDK 8u65 and the Let’s Encrypt certs are not included in the ca-store of this version.
The solution was to install a newer version of the jdk.
In my case i had to use the ppa-package of WEB UPD8: http://www.webupd8.org/2012/09/install-oracle-java-8-in-ubuntu-via-ppa.html and set this JDK as default.
After a reboot of the machine everything works fine! 
Maybe you can add this information to your FAQ, this could be helpful for people with the same problem.
Which Readme did you look at, the one for OH2.2 does included that in there: https://docs.openhab.org/addons/bindings/tankerkoenig/readme.html#preparation
Note: As long as OH2.2 isn-t releases as stable, the readme can be switched from 2.1 to 2.2.
I looked at https://docs.openhab.org/addons/bindings/tankerkoenig/readme.html#faq for the 2.2-snapshot.
There is the following section:
That indicates a missing certificate for the https-connection on the system. In order to get the required certificate on a Linux-system one needs to perform these steps:
sudo wget Notice to all StartCom subscribers
keytool -import -keystore cacerts -alias startssl -file ca.crt
But Tankerkönig now uses a ceritficate from Let’s Encrypt and they are compatible with java 8 since update 101
So the information in the FAQ is out-dated.
It’s required that openhab runs with a JDK which is compatible with the certificates from Let’s Encrypt
Maybe you can add the information, that you have to check the certificate from https://creativecommons.tankerkoenig.de and the keystore of the java version, if you have any connection problems.
Ah, you were talking about that!
My comment was referring to the new part of the readme that states the requirement for a java version newer then 1.8.0_101-b13 .
That the observed problem with a missing ssl certificate is obsolete when using a newer java version was/is not obvious to me. I’ll try to have a look into that.
Thanks for the input.
[Edit]
IMHO the way to get a/the certificate is a described in the readme, there is no way to get it from Tankerkoenig direct.
Does the use of an actual java version in some way automatically load the certificate without any user interaction ? I would need a completely clean system with an old java version to test that.
As long as such can be confirmed I think that FAQ should remain in the readme.
Yes the information how to install a certificate in a keyfile is correct. 
But the information that you should use the certificate from startssl is out-dated, because tankerkoenig now uses a certificate from Let’s Encrypt.
For me was the missing key-information, that you first have to check which certificate tankerkoenig is using and then check if it’s is in your java-keystore.
The way to import the certificate to the java-keystore is in my opinion just a workaround, because if you don’t update your jdk, you will get further ssl-connection-problems in future, when the certificates stored in the keystore expire.
It makes more sense to use a up-to-date jdk, because they update the keystore with the jkd-updates. So you would have no problems to connect to hosts with a certificate from a trusted certificate authory.
For all that, it could make sense to update the FAQ with more detailed information.
I would add the following:
- Check the certificate of https://creativecommons.tankerkoenig.de
- Check if it’s in your java-keystore (Maybe add a how-to, i can write somethig if you want)
- Add the certificate to the right keystore (determine which jdk you are using and where the keystore is stored, detailled how to)
- OR install a up-to-date java-version
- restart your machine
Shure that’s not a problem from the binding, but the information would help other users and they can save time. 
Just want to help
I have to admit that the description on how the load a certificate was only a paste and copy. My knowledge on that topic is very limited. My (false) understanding is/was that the posted description would load the actual certificate (IMHO Let’s encrypt is in use since the end of 2015).
I would really appreciate if you would write something. You can post it here or on github as an issue.
Hey,
I thought about a tutorial and i think this is a good description of the problem and the solution.
Maybe you want to update the FAQ of the version 2.2
-The Station(s) and Webservice stay OFFLINE
Set the logging level for the binding to DEBUG (Karaf-Console command: “log:set DEBUG org.openhab.binding.tankerkoenig”. Create a new Station (in order to start the “initialize” routine). Check the openhab.log for entries like:
2017-06-25 16:02:12.679 [DEBUG] [ig.internal.data.TankerkoenigService] - getTankerkoenigDetailResult IOException:
java.io.IOException: java.util.concurrent.ExecutionException: javax.net.ssl.SSLHandshakeException: General SSLEngine problem
That indicates a missing certificate of a certificate authority in the certificate-store of your java jdk under which your openhab2 runs.
In most cases it helps that you update to the latest jdk version, because the store of the cacerts are maintained with the java versions.
So you’ll get the missing certificate with the new java version.
After the java-update you have to restart your openhab2.
If you have an old linux installation which has only old java-versions in his package-repositories, you have three possibilities:
- Update your linux-system and install the latest java-versions
- Install a newer java-version on a different way
- on debian based systems u can use this: http://www.webupd8.org/2012/09/install-oracle-java-8-in-ubuntu-via-ppa.html
- Update the store of the cacerts / Import the missing certificate to the ca-store
- This ist the worst option, because in future you will have problems to access further websites with https, because the certificates of the certificate authorities in the ca-store will expire
If you still want to go the way with the import of the certificate you can use this as a little help:
- Check which java package you have installed:
>> sudo dpkg -l | grep java
>> ii oracle-java8-jdk 8u65 armhf Java™ Platform, Standard Edition 8 Development Kit
- Find the ca-store of your jdk
>> sudo dpkg -L oracle-java8-jdk | grep cacerts
>> /usr/lib/jvm/jdk-8-oracle-arm32-vfp-hflt/jre/lib/security/cacerts
- Check which certificate authory has validated the certificate
- In your browser, go to https://creativecommons.tankerkoenig.de/
- Check which certificate authority has validated the certificate
- Export the certificate of the certificate authority
- Import the certificate to the ca-store which you have found
>> cd /usr/lib/jvm/jdk-8-oracle-arm32-vfp-hflt/jre/lib/security
>> keytool -import -keystore cacerts -alias LetsEncrypt -file ca.crt
The required password is “changeit”.
- Restart your server
Do you think this is ok?
Thanks for that.
As stated before my knowledge on that topic is rather limited.
I did some changes in the wording and filed a pull request on Github.
Thanks for this binding.
I will try to get it to run.
I like your:
„Geben ist seliger als Nehmen“ 
I’m not yet able to give a lot back except some personal experience to share in one or the other post.
Anyway, is it also possible to get the cheapest station in a specific range to compare with my local one?
Good Morning and thanks for the feedback!
Some thoughts on your request:
The Tankerkoenig API does have such a request ( so it could be done). This request however returns a ( long) list of stations, showing only the one with the lowest price (for the selected gas type) would be one way. What do you think? What would you like to be presented for that station price, name, adress?
When it comes to coding that request, I like to postpone it a bit.
[Edit]
You made me start thinking about!
Such a request (search all stations in a range and determine the cheapest) would only be made ON CALL, wouldn’t that be better/more correctly implemented in an Action? Although I think doing such would be an overkill (creating an Action which is used by a single special case only).
Thanks for your quick response.
My main goal would be:
Check my standard station’s diesel price and compare with the cheapest one in around few km.
With this I could judge if my stardard stations price is far too high or reasonable (Telegram message if the difference is too high.
It’ not urgent, just consider this please for an future extension.
Hey,
I’m doing this in rules in some way already. I’m watching the price of 4 gas stations and persist the values with influx.
In case the gas price changes a rule is triggered that checks the chapest station and compares it to the minimum value of the last 3 days.
In case gas has the cheapest value since 3 days, I do send a telegram with the price and the station. Only enhancement on the list is putting all stations in a group and work on the group to easily add and remove stations.
I guess you are in a low crowds region like me. I’m persisting my local stations as well, however I’m mainly looking for what is the best daytime for refuelling.
Personally I would do something like @NCO requested in a rule as well, however the binding was made for users that don’t want to or can’t handle JSON responses. So…
Sounds great.
I persist in MySQL on my nas, but would be interested in your rule.
Because I also use Telegram as th central messaging tool, I could almost use your rule without significant changes
thats sounds good,
could you please post your items, rules files please?
Its a straight forward setup. The items are default. And as I said, I havent done “group” enhancement jet.
Here’s a sample item:
Number diesel_jet_berliner
"Diesel Jet Berliner [%.3f Euro]"
<gas_station>
(gAllgemein,gSprit)
{ channel="tankerkoenig:station:3cc3915d:diesel" }
Number diesel_cheapest_3d
"Günstigster Diesel 3T [%.3f Euro]"
<gas_station>
(gAllgemein,gSprit)
And this is the corresponding rule:
rule "Diesel Jet günstiger"
when
Item diesel_jet_berliner changed
then
var Number cheapest_sprit = (diesel_jet_berliner.minimumSince(now.minusDays(3), "influxdb").state as DecimalType)
diesel_cheapest_3d.postUpdate(cheapest_sprit)
//logInfo("Sprit Preise", "Der günstigste Sprit Preis seit 3 Tagen ist: " + cheapest_sprit )
if( diesel_jet_berliner.state <= cheapest_sprit ){
sendTelegram("gruppe", diesel_jet_berliner.label + " ist mit " + diesel_jet_berliner.state + " Euro seit 3 Tagen am günstigsten")
// } else {
// logInfo("Sprit Preise", diesel_jet_berliner.label + " war in den letzten 3 Tagen mit " + cheapest_sprit + " Euro schon mal billiger als jetzt mit " + diesel_jet_berliner.state + " Euro" )
}
end
For debugging you can remove the comments and have more logging.
Hope this helps.
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